Ovidiu Anton

Ovidiu Anton is a Romanian singer and songwriter. He was supposed to represent Romania in the Eurovision Song Contest 2016, but was disqualified from the contest due to his government’s repeated non-payment of debts to the European Broadcasting Union.

Mary Boullay’s mother is from Baden so it’s safe to say she’s German, her father is also likely German. Boullay was probably something like Buehle. Sigmond appears to be Polish from Vilnius. Frances’ parents are Polish from Russian part of Poland.
Italian part is Italian.
I’d say he’s what it already says on his page.

His grandmother’s brother is also called Constantine, which, while not impossible, is an odd name for a Jew. Wasn’t Constantine the first Christian king?
And Didimamoff doesn’t even exist outside the US (variants Didiamoff and Didimamow were used on some documents, also non-existant outside US). Only thing that comes even remotely close is a Greek name Didymous (and that doesn’t appear to be in use since 5th century AD).